Ground surface and poly-urethane (PU) filling alter the pressure distribution pattern in square standing horses

Abstract

This study was conducted to evaluate the effects of Pour-In, Poly-Urethane (PIPU) products on pressure distribution underneath the hoof and shoe, as many farriers report the successful use of these products in cases where horses suffer from a reduced bearing surface. The tested hypotheses were that shoes filled with PU would increase the bearing surface and thus provide lower mean pressures and that these effects would be the same despite the deformability capacities of the surface the horses stood on. Data were collected from 6 clinically sound Warmblood horses while standing on top of a pressure/force measuring device. The horses had been shod at random with regular steel shoes and the same shoes filled with PU. Data were collected on 2 different ground surfaces, a firm, rubber surface, and a deformable, sand surface. With PU filling the bearing surface underneath the shoe did not increase significantly, nor did the mean pressure decrease. On a firm surface the pressure distribution pattern is similar in both shoeing conditions. On a deformable surface the shoe filled with PU has a significantly different (p<0.05) pressure distribution pattern and mainly the sole and the frog became loaded. With the use of PIPU the pressure distribution pattern underneath the shoe and hoof, is altered. These findings will aid to explain why so many farriers use PU products successfully in horses with a defect in their hoof wall or loss of bearing surface. On the other hand there seems no reason to shoe sound horses without problems in their feet with PIPU to provide 'total foot support'. It might even have negative effects on horses with normal healthy feet which are trained on a deformable, sand surface, since normal loading of the hoof should occur mainly on the hoof wall instead of the frog and sole being the only weight bearing structures.